Patients with low renin hypertension have low renin and angiotensin II concentrations but aldosterone values which are normal and, therefore, inappropriately high in relation to the suppressed renin. Previous studies have indicated that sodium-retaining steroids other than aldosterone are not involved in the maintenance of hypertension in these patients. Among other explanations is the possibility that the adrenal receptor sensitivity to angiotensin II is increased in patients with low renin hypertension. This protocol evaluates that hypothesis by examining the aldosterone response to infused Angiotensin II in normotensive subjects and in low renin hypertensive patients. Four patients with low renin hypertension and 2 normotensive subjects have been studied but the results are currently insufficient to reach any conclusions.